Arrangement of opposed superchargers



Jan. 26, 1954 c, R,'w s 2,667,298

ARRANGEMENT OF OPPOSED SUPERCHARGERS Filed June 17, 1948 4 Sheets-Sheet l J fliiorney Jan. 26, 1954 c. R. WELLS 2,657,293

ARRANGEMENT OF QPPOSED SUPERCHARGERS Filed June' 17. 1948 4 Sheets-Sheet 2 5. Wm W e awn v m. 2 u %fl 1 s 7w \& mum 0 3 $1 N0 QQ II) fl Q Q Q %Q\ m QR Um mm m mm m, v M% %w & m 1 mm W 8\ r) T M ww 26, 1954 c. R. WELLS 2,667,298

ARRANGEMENT OF OPPOSED SUPERCHARGERS Filed June 17, 1948 4 Sheets-Sheet a In 112741 02 (71 esierfl. 762275 220 rm 9y Jan. 26, 1954 c. R. WELLS ARRANGEMENT 0F OPPOSED SUPERCHARGERS 4 Sheets-Sheet 4 Filed June 17, 1948 Patented Jan. 26, 1954 ARRANGEMENT OF OPPOSED SUPER-CHARGERS Chester R. Wells, Rocky Hill, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application June 17, 1948, Serial No. 33,456

15 Claims. 1 This invention relates to superchargers and particularly to an arrangement of a pair of superchargers arranged to operate in parallel.

Where conditions are such that the required quantity of air for supercharging cannot be delivered by a single impeller Wheel, the size of which is limited by the engine installation, it may be advantageous to operate supercharger wheels in parallel. A feature of this invention is an arrangement of supercharger wheels on opposite sides of a crankcase section with a common drive from the engine for both wheels.

When superchargers are so arranged, the thermal expansion of the crankcase section may change the spacing between the supercharger casings and thus produce an undesirable change in the clearance between the interconnected supercharger impellers and the adjacent walls of the casings especially where the opposite impellers are directly connected together. A feature of this invention is an arrangement by which to compensate for the change in the spacing of supercharger casings by producing a corresponding change in the spacing of the impellers. More specifically, a feature of the invention is the interconnection of the impellers in such a manner that the impellers will be caused to move apart axially the same amount that the casings are moved during thermal expansion of the supporting crankcase section;

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustrate an embodiment of the invention.

Fig. l is a vertical sectional view through an 'airplane nacelle showing the installation of the two stage engine.

Fig. 2 is a perspective view showing the arrangement of the auxiliary supercharger stage.

Fig. 3 is a longitudinal vertical sectional view through the rear section of the engine.

Fig. 4 is a horizontal sectional view along the line 44 of Fig. 3.

Fig. 5 is a view of a part of Fig. 4 on a somewhat larger scale showing the construction of the impeller shaft and showing the coupling assembly in section. I

Referring first to Fig. 1, showing an engine with two stages of supercharge, the airplanenacelle 2B encloses an aircraft engine 22 supported as by a frame 24, the engine being connected to the frame as by mounting brackets 26. The engine shown is of the multiple-row radial type in which thecrankcaseZB supports the cylinders 30 and has a nose section 32 incorporating the reduction gear, not shown, for the propeller system 34. The nose section also carries one or more accessories 36.

Crankcase 28 has a rear section 38 within which is enclosed the main supercharger and its drive together with a drive for other accessories 40 hereinafter described in greater detail. The rear section supports on opposite sides the casings 42 and $4 for the impellers of the auxiliary supercharger stage.

Air enters the supercharger casings through ducts 4B and 48, Fig. 1, communicating with the centrally located openings 43 and 45, Fig. 4, in the casings 42 and 44. Air compressed by the auxiliary compressor stages may be discharged from the casings 42 and 44 into one or more inter-1 coolers and thence to the duct 52 leading to the carburetor 54 and from there to the main supercharger 56, Fig. 3. A flap valve 58 may be provided in the duct 52 to admit air directly from an inlet 60 to the main supercharger stage when the auxiliary stage is not in operation.

Referring now to Fig. 3, the impeller 62 for the main supercharger stage is driven from the accessory drive shaft 64 which is connected to the crankshaft 66 by a change speed gearing. This gearing includes a fixed ring gear 68 meshing with one or more pinions or planet gears 10 on a shaft 12 in a cage '14 attached to the end of the crankshaft. The planet gear, of which there would normally be a group spaced circumferentially around the crankshaft, meshes with a sun gear 16 on the accessory shaft to drive the accessory shaft substantially faster than the crankshaft and preferably at a speed three times that of the crankshaft. This specific arrangement of drive is described and claimed in the copending Hasbrouck application Serial No. 33,515, filed June 17,1948 now Patent No. 2,595,942.

The accessory shaft 64 carries a driving gear 18, the hub of which is splined to the shaft and provides a bearing surface for the shaft within a bracket which is fastened within the crankcase section 38. The gear 18 meshes with a gear 32 on a shaft 84 journalled in the bracket 80 and ina bearing 86 provided by the rear crankcase section. Shaft 84 carries another gear 88 meshing with a gear 90 splined to the sleeve 92 on which the impeller 62 is mounted. The supercharger casing 54, within which the impeller 52 is located, interconnects the main crankcase section 26 and the rear section 38.

The accessory shaft also drives other accessories, such as the starter or generator 40 through a series of interconnecting gears I00 connecting r with a gear I02 also splined to the accessory shaft 54. The particular accessory drive arrangement is described in the copending application of Hasbrouck Serial No. 33,515, filed June 17,1948 now Patent No. 2,595,942.

As shown in Fig. 4, the drive for the auxiliary stage impellers I84 and I86 is from the same gear I8 that drives the main impeller. The impellers I04 and I06 are mounted on opposite ends of a shaft assembly I III driven in the low speed range through a' gear II2 meshing with gear 18 and a low ratio hydraulic coupling II4 delivering power to a bevel gear I I6 meshing with a pinion II8 having a drive connection with the shaft assembly I Ill. The auxiliary stage impellers are driven in the high speed range through a gear I20 in mesh with the gear 18 and meshing in turn with a gear I22. The latter drives a bevel gear I24 through a hydraulic coupling I26, the bevel gear I24 meshing with a pinion I28 connected to the impeller shaft assembly IIII. The shaft assembly includes a central impeller connecting rod I30 having tie bolts I32 and I34 threaded into opposite ends of the rod and forming extensions of it. Each bolt has a flange I35, Fig. 5, engaging the end of the rod and each bolt is' fastened in the rod by a pin I38. The

impellers I84 and I88 are mounted on sleeves I40 and I42, preferably with a shrink fit, and are clamped thereon as by a nut I44. The sleeves I40 and I42 are mounted on the ends of the connecting rod and associated tie bolts, and are clamped thereon by nuts I46. Each of the sleeves has an internal shoulder I48 engaging with a spacer ring I50 to maintain the desired spacing between the impellers.

The inner ends of sleeves I48 and I42 are both splined to a connecting quill I52 in such a manner that the sleeves will rotate in unison although they are free to move axially with respect to each other. The sleeves I48 and I42, and the connecting rod I38 and tie bolts I32 and I34, form, with quill I52, the shaft assem- -bly III) that interconnects the impellers.

Each sleeve I48 and I42 has a driving hub I53, Fig. 5, mounted thereon and having a spline connection I54 with the associated sleeve. Each hub has an annular flange I56 receiving a centrally located boss I53 on'the adjacent impeller for driving it. Thus both impellers rotate as as unit on the interconnecting shaft assembly which permits thermal expansion between the opposed impellers.

For driving the shaft assembly III), the'sleeves 148 and I42 carry surrounding sleeves I62 and IE4 splined to the sleeves I48 and I42, respectively, and axially slidable thereon, the outer surrounding sleeves forming bearing surfaces for the shaft assembly. The shaft assembly is 'ijournalled centrally in bearings I88 in the bracket 88 mounted, as above stated, in the rear crankcase section 38. Adjacent each impeller, as best shown in Fig. 5, the assembled shaft is journalled in bearing sleeves I61 and I69 in backing plates "I68 and Ill! (Fig. 4), respectively,'which form the back walls of the impeller casings 42 and "44. These plates I58 and I18, as shown in Figs. 4 and 5, are mounted on opposite sides ofthe crankcase section 38. bearings for the assembled shaft, the plates form the back closure plates for the casings 42 and In addition to providing 44. The front plates or scrolls I12 and I18 for the casings are attached at their edges to the plates I88 and I18 respectively, and support the I diffuser rings I14 and I15.

The plates I68 and I18 are arranged to support the driving mechanisms for the auxiliary supercharger stage. As best shown in Figs. 4 and 5, the plate I88 provides bearings I16 for the shaft I18 for the low ratio drive. The plate I19 provides similar bearings I88 for the shaft I82 of the high ratio drive. The drive connections for the low and high ratio drives for the supercharger stage are similar, except for the gear ratio, and a description of the low ratio drive will suffice. As shown in Fig. 5, the gear H2 is splined to a sleeve I86 on which the impeller I88 of the low ratio coupling H4 is mounted. The runner I90 of the coupling is splined to the shaft I18 to which the bevel gear H6 is also tion with the sleeve I82 and is held in fixed axial position thereon by locking rings I96. The gear H8 is backed up by a thrust bearing ring I98 which engages with a cooperating ring 200 supported by the bearing ring I61 in plate I68 for limiting the axial movement of the gear IIB. Gear I28 is fastened to sleeve I64 in a similar manner and is backed up by a thrust bearing 282, Fig. 4. The assembled shaft is free to slide axially within the sleeves I62 and I64, thereby permitting the axial thrust on the opposed impellers to balance out. It may be noted that the gears H8 and I28 are retained in predetermined relation to the axes of gears IIB and I24 by the thrust bearings and independently of the thermal expansionof the crankcase section 38 since the gears I18 and IIB are both supported by the plate I68 and both gears I28 and I38 are supported by the'plate I18.

The material of the impeller connecting rod I38 is so selected that its total longitudinal thermal expansion will correspond almost exactly to the total transverse thermal expansion of the crankcase section 38. Thus, if the plates I58 and I18 are caused to move apart by the thermal expansion of the'crankcase section, the corresponding thermal expansion of the rod I30 will produce an increase in the. spacing between the impellers I84 and I08, thereby to assure a maintenance of the proper clearance between the impellers and the adjacent surfaces of the surrounding casing regardless of the operating temperature of the parts of the power plant.

Since the normal operating temperature of the rod I36 may be different from the normal operatingtemperature of crankcase section 38, the length and material of rod I38 for the purpose of equalizing the thermal expansions, may be determined by tests by which the operating temperatures and, therefore, the required changes in dimension may be ascertained. In the arrangement shown, a magnesium rod was used in conjunction with a magnesium rear crankcase section, and the rod was made nearly the same length as the transverse dimension of the rear case. Obviously, other dimensions and material might be used where necessary to balance the thermal expansions. V

In assembly of the auxiliary superchargers, the sleeves I62 and IE4 are mounted within the supporting plates I58 and I18 and in the bearings I68 in bracket 8'8. Quill I52 is placed in position before assembly of the sleeves I62 and.

" I54. One of theimpellers with its attached sleeve is then mounted and the central shaft with its plates. part of the sub-assembly of the driving mechaattached bolts is inserted. The other impeller and sleeve are then added and the clearance for the impellers are checked. The proper clearance is obtained by inserting a spacer ring or spacer 1'50 of the necessary length, The clamping nuts I46 are then tightly secured and the impeller assembly is complete. The diffuser elements and the scrolls are then placed in position over the impellers and secured to the remainder of the unit. It will be apparent that the sleeves I62 and I64 may have been mounted in proper relation to the plates :68 and H0 during the as sembly of the impeller driving means on said The sleeves Hi2 and H36 will then be a nism and fluid coupling that is mounted. on the plate I68 or I10.

I claim: 1. In a power plant, an engine and a supercharger arrangement, the latter including an impeller mounted on each side of said engine, a shaft assembly connecting said impellers and being supported by said engine, two separate driving means mounted between said engine and said shaft assembly for selectively driving the impellers, each driving means including a surrounding sleeve mounted around said shaft assembly and being splined thereto.

2. In a power plant, an engine and a supercharger arrangement, the latter including an impeller mounted on each side of said engine, a shaft assembly connecting said impellers and being supported by said engine, two separate driving means mounted between said engine and said shaft assembly for selectively driving the shaft, a pair of supercharger impellers, one

mounted on each side of said engine, a shaft assembly connecting said impellers, two separate driving means mounted between said crankshaft and said shaft assembly, each driving means including a hydraulic coupling and a surrounding sleeve mounted around and splined to said shaft assembly.

5. In a power plant, an engine having a crankshaft, a pair of supercharger impellers, one mounted on each side of said engine, a shaft assembly connectingsaid impellers, two separate driving means mounted between said crankshaft and said shaft assembly, each driving means including a hydraulic coupling, gearing for transmitting the drive from the crankshaft to the coupling and a bevel gearing for transmitting the drive from each coupling to the impeller shaft assembly, each bevel gearing including a bevel gear connected to a surrounding sleeve mounted around said shaft assembly, each surrounding sleeve being splined to said shaft assembly.

6. In a supercharging device, a supporting member, a supercharger mounted on each side of said member, each supercharger including an impeller, and a shaft assembly journalled in said memberand extending between and supporting said impellers, said shaft assembly including. a connecting rod, a sleeve mounted on each end of said rod for supporting said impellers, and a quill surrounding the inner ends of said impeller supporting sleeves and being splined thereto.

7. In a supercharging device, a supporting member, a supercharger mounted on each side of said member, each supercharger including an impeller, and a shaft assembly journalled in said member and extendingbetween and supporting said impellers, said shaft assembly including a connecting rod, a sleeve mounted on each end of said connecting rod, said sleeves supporting the impellers, and tie bolt means mounted on the ends of the connecting rod for securing the sleeves to their respective ends of the connecting rod.

8. In a supercharging device, a supporting member, a supercharger mounted on each side of said member, each supercharger including an impeller, and a shaft assembly journalled in said member and extending between and supporting said impellers, said shaft assembly including a connecting rod, a sleeve mounted on each end of said connecting rod, means supporting each sleeve against axial movement on the rod at the end thereof, saidsleeves supporting the impellers, said connecting rod being of a material to have a thermal expansion equal to the thermal expansion of the supporting member.

9. In a supercharger arrangement, a supporting member, superchargers fixedly mounted on opposite sides of said member each including an impeller and a casing, and a shaft assembly supported by said member and supporting said impellers including a connecting rod, a sleeve mounted on each end of said connecting rod,

means supporting each sleeve against axial movement on the rod at the outer ends thereof, a quill surrounding the inner ends of said sleeves and impeller mounted on each side of said engine, a shaft assembly connecting said impellers and being supported by said engine, and two separate driving means mounted between said engine and saidshaft assembly for. selectivelyndriving the impellers, said shaft assembly including, a con.-

.necting rod and a sleeve mounted and fixed on each end of saidrod, each driving means having a surrounding sleeve mounted around one of said sleeves of said shaft assembly, each surrounding sleeve being splined to its cooperating shaft assembly sleeve. v

11. In a power plant, an engine and a supercharger arrangement, the latterincluding animpeller mounted on .each side of said engine, a

shaft assembly connecting said impellers and being supported by said engine, and two separate driving means mounted between said engineand said shaft assembly for selectively driving the impellers, said shaft assembly including a con necting rod, a sleeve mounted on saidconnecting each sleeve against axial movement on the rod at the outer ends thereof and a quill surrounding the inner ends of said sleeves and being splined thereto to permit'tne sleeves to rotate in unison while leaving them free to move axially with respect to each other, said sleeves supporting th'e impellers at their outer ends, each driving means having a surrounding sleeve mounted around and attached to one of said shaft assembly sleeves and being located between said quill and said impeller.

12. In combination, an engine, a supercharger mounted on each side of said engine, each supercharger including a casing and an impeller, a shaft assembly mounted in said engine and supporting said impellers, said shaft assembly including a connecting rod, a first sleeve having one end boltedto one end of said rod,'a second sleeve having one end bolted to the other end of said rod, the free ends of said sleeves being positioned intermediate the ends of said rod, and a quill surrounding the free ends of said sleeves and bein splined thereto, one impeller bein mounted on the bolted end of each of said sleeves.

13. In combination, an engine, a supercharger mounted on each side of said engine, each supercharger including a casing and an impeller, a shaft assembly mounted in said engine and supporting said impellers, said shaft assembly including a connecting rod, said rod having an internally threaded recess at each end, a first sleeve having two internal bores of different diameters, the larger of the two bores having sliding engagement with one end of said rod, a first tie bolt, said first bolt being threadably engaged at one end in the internally threaded recess of said one end of said rod and extending through the smaller of the two bores of said sleeve, a first nut threadably engaging the other end of said first tie bolt to hold said first sleeve on said connecting rod, a second sleeve having two internal bores of difierent diameters, the larger of the two bores having sliding engagement with the other end of said rod, a second tie bolt, said second bolt being threadably engaged at one end in the internally threaded recess of said other end of said rod and extendin through the smaller of the two bores of said second sleeve, a second nut threadably engaging the other end of said second tie bolt to'hold said second sleeve on said connecting rod, the free ends of said sleeves being positioned intermediate the ends of said rod. and a quill surrounding the free ends of said sleeves and being splined thereto, one impeller being mounted on the bolted end of each of said sleeves.

14. In combination, an engine, a supercharger mounted on each side of said engine, each supercharger including a casing and an impeller, a shaft assembly mounted in said engine and supporting said impellers, said shaft assemblyineluding a connecting rod, said rod having an internally threaded recess at each end, a first sleeve having two internal bores of "different diameters, the larger of the two bores having sliding engagement with one end of said rod, a first tie bolt, said first tie bolt being threaded on each end and having a flange at the end of the threaded portion of one end, said'first tie bolt being threaded into one threaded recess of said rod with the'flange of said bolt resting against the end of said rod, said tie bolt extending through the smaller of the two bores of said sleeve, a

first nut threadably engaging the other end of said first tie bolt to hold said first sleeve on said connecting rod, a second sleeve having two inthe end of said rod, said tie bolt extending through the smaller of the two bores of said second sleeve, a second nut threadably engaging the other end of said second tie bolt to hold said second sleeve on said connecting rod, the free ends of said sleeves being positioned intermediate ternal bores of diiferent diameters, the larger 7 of the two bores having a sliding engagement sleeves.

the ends of said rod, and a quill surrounding the free ends of said sleeves and being splined thereto, one impeller being mounted on the bolted end of each of said sleeves.

15. In combination, an engine, a supercharger mounted on each side of said engine, each supercharger including a casing and an impeller, a shaft assembly mounted in said engine and sup;- porting said impellers, said shaft assembly including a connecting rod, said rod having an internally threaded recess at each end, a first sleeve having two internal bores of difierent'diameters, the larger of the two bores having sliding engagement with one end of said rod, a first tie bolt,

said first tie bolt being threaded on each end and 7 having a flange at the end of the threaded portion of one end, said first tie bolt being threaded into one threaded recess of said rod with the flange of said bolt resting against the end of said rod, said tie boltfextending through the smaller of the two bores of said sleeve, a first spacer located between the flange and the shoulder formed by the intersections of the bores of difierent diameters in the first sleeve, a first'nut threadably engaging the other end of said first tie bolt to hold said first sleeve on said connecting "rod, 2. second sleeve having two internalbore's 'formed by the intersections of the bores of different diameters in th second sleeve, a second nut threadably engaging the other end of said second tie bolt to hold said second sleeve on said connecting rod, the free ends of said sleeves being positioned intermediate the ends of said rod, and a quill surrounding the free ends of said sleeves and being splined thereto, one impeller bein mounted on the bolted end ofeach of said 7 CHESTER, R. WELLS.

References Cited in the file of this patent- UNITED STATES PA'IENTS Number Name Date 1,874,681 Woolson Aug. 30, 1932 2,142,269 Gossler Jan. 3, 1939 2,233,889 Kollmann Apr. 22, 1941 2,346,032 Kinnucan .Apr. 4, 1944 2,371,983 Forsyth et a1 Mar. 20; 1945 2,393,172

Larrecq Jan. 15, .1946 

